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Temperature Guage Needle Bouncing

Ugh! My trusty CR-V is starting to give me a headache! Recently it started doing this thing where the temperature guage needle starts bouncing up and down as the engine warms up after a mile or so down the road. It will eventually settle back down into the normal range and then be fine from then on. This happens 1st thing in the morning leaving for work coming out of a heated garage. My car sits outside all day long while at work. Daytime temps have been hovering around 35-40°. When I leave work, the temperature guage will climb steadily and continue to rise into the hot zone until it’s pegged. The last couple of days it did this so I pulled over and shut the car off. I waited a couple of minutes before turning the car back on. When I restarted, the guage slowly came down from hot and fell back into the normal range, where it stayed without any issues all the way home, which is about 15 miles from where I work. The coolant is topped off. There are no leaks coming from under the front of the car. Is this a thermostat issue or something else? Please help this damsel in distress in Northern Michigan!!

Could be, but I would check the coolant temperature sensor first.

That does sound like a failing thermostat, I have seem cases where there was a delayed opening of the thermostat. First be sure that the cooling system is full.

How old is yjis CRV and how long have you had it? Have you ever had the coo;snt strength tested?

It’s an '02, owned for about 5 years, and ‘no’ on testing strength of coolant.

Thanks for the response. I will mention to my mechanic. :grinning:

Yes, it is topped off.

Get the coolant changed if you never did it. While it’s drained, have the mechanic inspect the thermostat. Given that your ride is 17 years old, you might consider replacing the thermostat while it’s out.

Thank you! :slight_smile:

If you get this fixed, it would be nice to know what the solution was.

I will keep you posted. Thank you! :slight_smile:

If you’re going to replace the thermostat, I recommend you buy the part from a Honda dealer

You don’t want to take a chance that a store-brand part is “good enough” . . .

I’m speaking from experience here

Good tip–thanks!!

I’m guessing one or more of these

  • Coolant level is low or system isn’t holding pressure, faulty pressure cap, or small leak. (Do you have to add coolant to keep it topped up? If the radiator has a separate cap, be sure to check the coolant level in the radiator, not just the level in the plastic bottle.)
  • Air in cooling system (do you hear any sounds like water rushing or bubbling through a pipe, esp when the heater is turned on and you rev the engine a little?)
  • Faulty thermostat
  • Faulty water pump
  • Incontinent head gasket

If you hardly ever have to add coolant to keep it topped up and there’s no signs of air in the coolant or external leaks, and the thermostat is over 3 years old, replacing the thermostat on a flyer makes sense . I have to say however that this sounds like the cooling system is either low or not holding pressure, rather than a thermostat problem.

Thanks for the response!
I called my mechanic the other day b/4 leaving work and told him what was going on. He said the same thing–that it may be low on cooIant. He suggested I add some more and to mark the level on the reservoir to see if it went down after driving it. I checked the reservoir level an hour or so after I got home and nope–the fluid was right where I had marked it. It is showing full when I take off radiator cap, as well. He also mentioned the coolant temperature sensor, which was mentioned by kurtwm1 in a previous response. I believe he is going to switch that out to see if that fixes it. The problem is so intermittent. I left my house a few hours ago to run into work and the temp guage performed flawlessly. (My car is parked in the garage/workshop, which is heated.) Was there for about 2 1/2 hours and went back home. Again, no issues.
The guage really acts up after my car has sat outside for a few hours in colder temps–say 20 - 30°. Then the temp guage wants to climb all the way up to hot after a couple miles down the road.
I appreciate everyone’s knowledge and response with this issue and helping me get this figured out. I will keep you all posted with the results. :+1:

The thermostat is not opening promptly and should be replaced.

I’ll say what nobody else apparently has . . .

You need to measure the actual coolant temperature with a separate thermometer . . . for example one of those infrared laser thermometers that you can buy at an auto parts store and probably even harbor fake these days

What if your coolant temperature sensor is in fact telling you the truth . . . ?!

By the way, coolant temperatures can easily be tested with a multimeter, if you have the chart which shows the correlation of temperature versus resistance

You can also test the accuracy of the coolant temperature gauge by simulating various temperatures with your decade resistance box. Again, you need that chart I mentioned